Reference library

Testing & modern typing

pytest basics, mocks, type hints, TypedDict, Protocol, and static-checking patterns.

3 matches

Design Data Helpers with Python TypedDict and Literal

Use TypedDict, Literal, and Union to define typed data shapes and parse values in Python.

from typing import TypedDict, Literal, Optional, Union, List

class User(TypedDict):
    name: str
    age: int
    role: Literal["admin", "user", "guest"]

def describeUser(data: User) -> str:
    return f"{data['name']} ({data['age']}) — {data['role']}"

def parse_value(item: Union[int, str, None]) -> str:
    if it…

12 0 Open

Testing & modern typing easy

How to Use Literal Type Hints in Python

Use typing.Literal to restrict a function parameter to specific allowed string values and get static type checking.

typing type-hints literal

Python

from typing import Literal

def get_status_message(status: Literal["active", "inactive", "pending"]) -> str:
    """Return a message based on the status value."""
    if status == "active":
        return "Account is active"
    elif status == "inactive":
        return "Account is inactive"
    else:
        return "…

15 0 Open

Testing & modern typing medium

How to Use Mock Flip Mutation Testing in Python

Demonstrates how mutation testing tools flip Boolean literals (mock flip) in Python source to verify test suite effectiveness in catching logic changes.

mutation-testing testing bool

Python

import random

# In mutation testing, a "mock flip" intentionally changes a Boolean
# constant to False (or True) to see if the test suite catches it.
# This is a common "constant mutation" applied to a source file's literals.

def is_even(n: int) -> bool:
    """Return True if n is even. Contains a Boolean literal us…

13 0 Open

Browse by section

Each section groups closely related Python snippets.